At IU, how do I configure ArcGIS for license service failover?

At Indiana University, UITS manages a two-server Unix
system to provide automated failover licensing support for Esri software. The
primary and secondary UITS-managed Esri license servers are esri1
and esri2, respectively. To ensure uninterrupted access to
the license service, UITS recommends that you configure
your computer for license server failover by creating a system
environment variable specifying the names and port numbers of the Esri
license servers.

You must have administrative rights to make the following changes
to your computer; log in as an administrator if necessary.